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Subject[RFC/RFT PATCH 3/6] uvcvideo: Protect queue internals with helper
Date
From: Kieran Bingham <kieran.bingham@ideasonboard.com>

The URB completion operation obtains the current buffer by reading
directly into the queue internal interface.

Protect this queue abstraction by providing a helper
uvc_queue_get_current_buffer() which can be used by both the decode
task, and the uvc_queue_next_buffer() functions.

Signed-off-by: Kieran Bingham <kieran.bingham@ideasonboard.com>
Reviewed-by: Laurent Pinchart <laurent.pinchart@ideasonboard.com>
---
drivers/media/usb/uvc/uvc_queue.c | 34 +++++++++++++++++++++++++++-----
drivers/media/usb/uvc/uvc_video.c | 7 +------
drivers/media/usb/uvc/uvcvideo.h | 2 ++-
3 files changed, 32 insertions(+), 11 deletions(-)

diff --git a/drivers/media/usb/uvc/uvc_queue.c b/drivers/media/usb/uvc/uvc_queue.c
index c8d78b2f3de4..0711e3d9ff76 100644
--- a/drivers/media/usb/uvc/uvc_queue.c
+++ b/drivers/media/usb/uvc/uvc_queue.c
@@ -399,6 +399,34 @@ void uvc_queue_cancel(struct uvc_video_queue *queue, int disconnect)
spin_unlock_irqrestore(&queue->irqlock, flags);
}

+/*
+ * uvc_queue_get_current_buffer: Obtain the current working output buffer
+ *
+ * Buffers may span multiple packets, and even URBs, therefore the active buffer
+ * remains on the queue until the EOF marker.
+ */
+static struct uvc_buffer *
+__uvc_queue_get_current_buffer(struct uvc_video_queue *queue)
+{
+ if (!list_empty(&queue->irqqueue))
+ return list_first_entry(&queue->irqqueue, struct uvc_buffer,
+ queue);
+ else
+ return NULL;
+}
+
+struct uvc_buffer *uvc_queue_get_current_buffer(struct uvc_video_queue *queue)
+{
+ struct uvc_buffer *nextbuf;
+ unsigned long flags;
+
+ spin_lock_irqsave(&queue->irqlock, flags);
+ nextbuf = __uvc_queue_get_current_buffer(queue);
+ spin_unlock_irqrestore(&queue->irqlock, flags);
+
+ return nextbuf;
+}
+
struct uvc_buffer *uvc_queue_next_buffer(struct uvc_video_queue *queue,
struct uvc_buffer *buf)
{
@@ -415,11 +443,7 @@ struct uvc_buffer *uvc_queue_next_buffer(struct uvc_video_queue *queue,

spin_lock_irqsave(&queue->irqlock, flags);
list_del(&buf->queue);
- if (!list_empty(&queue->irqqueue))
- nextbuf = list_first_entry(&queue->irqqueue, struct uvc_buffer,
- queue);
- else
- nextbuf = NULL;
+ nextbuf = __uvc_queue_get_current_buffer(queue);
spin_unlock_irqrestore(&queue->irqlock, flags);

buf->state = buf->error ? UVC_BUF_STATE_ERROR : UVC_BUF_STATE_DONE;
diff --git a/drivers/media/usb/uvc/uvc_video.c b/drivers/media/usb/uvc/uvc_video.c
index 17a40c9a1fa3..045ac655313c 100644
--- a/drivers/media/usb/uvc/uvc_video.c
+++ b/drivers/media/usb/uvc/uvc_video.c
@@ -1322,7 +1322,6 @@ static void uvc_video_complete(struct urb *urb)
struct uvc_streaming *stream = uvc_urb->stream;
struct uvc_video_queue *queue = &stream->queue;
struct uvc_buffer *buf = NULL;
- unsigned long flags;
int ret;

switch (urb->status) {
@@ -1343,11 +1342,7 @@ static void uvc_video_complete(struct urb *urb)
return;
}

- spin_lock_irqsave(&queue->irqlock, flags);
- if (!list_empty(&queue->irqqueue))
- buf = list_first_entry(&queue->irqqueue, struct uvc_buffer,
- queue);
- spin_unlock_irqrestore(&queue->irqlock, flags);
+ buf = uvc_queue_get_current_buffer(queue);

stream->decode(uvc_urb, buf);

diff --git a/drivers/media/usb/uvc/uvcvideo.h b/drivers/media/usb/uvc/uvcvideo.h
index e4bd3d68a273..f274c685087d 100644
--- a/drivers/media/usb/uvc/uvcvideo.h
+++ b/drivers/media/usb/uvc/uvcvideo.h
@@ -692,6 +692,8 @@ extern int uvc_queue_streamon(struct uvc_video_queue *queue,
extern int uvc_queue_streamoff(struct uvc_video_queue *queue,
enum v4l2_buf_type type);
extern void uvc_queue_cancel(struct uvc_video_queue *queue, int disconnect);
+extern struct uvc_buffer *
+ uvc_queue_get_current_buffer(struct uvc_video_queue *queue);
extern struct uvc_buffer *uvc_queue_next_buffer(struct uvc_video_queue *queue,
struct uvc_buffer *buf);
extern int uvc_queue_mmap(struct uvc_video_queue *queue,
--
git-series 0.9.1
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